Featured Research

from universities, journals, and other organizations

After Drought, Diversity Dries Up And Ponds All Look The Same

Date:
October 17, 2007
Source:
Washington University in St. Louis
Summary:
An ecologist has discovered that after ponds dry up through drought in a region, when they revive, the community of species in each pond tends to be very similar to one another, like so many suburban houses made of ticky tacky.

WUSTL senior Ruth Poland and Jonathan Chase, Ph.D., associate professor of biology and director of WUSTL's Tyson Research Center, check species out in one of Tyson's ponds.
Credit: Washington University in St. Louis

An ecologist at Washington University in St. Louis has discovered that after ponds dry up through drought in a region, when they revive, the community of species in each pond tends to be very similar to one another, like so many suburban houses made of ticky tacky.

Jonathan M. Chase, WUSTL associate professor of biology in Arts & Sciences, and director of the university's Tyson Research Center, created 20 artificial ponds out of tanks that hold 300 gallons of water. He made each pond community exactly the same in their environmental conditions, but varied the timing in which he added many species to the community-- lots of species, especially dragonflies, water-bugs, frogs, and even algae, happily colonized the ponds on their own accord.

As the communities thrived, most of the ponds diverged from each other -- some had only between 10 and 20 percent of species in common with other ponds. This factor was due to stochasticity, or randomness --  a plant introduced by a seed dropped from a duck, a frog having a lucky day, for instance.

But then Chase, having played beneficent god, played pernicious god, adding drought, normally random in nature, to one-half of the pond environments.

"After the drought, the communities converged, and every community looked similar to each other," said Chase, who studies community assembly, among other areas of ecology. "It's understandable that only certain kinds of species can stand the drought. When it comes to drought, there are wimpy species and hardy species. Several types of zooplankton, many water-bugs, and some frogs are the hardy ones. A wimpy species, perhaps surprisingly, is the bullfrog. Their tadpoles require two years to grow, so they often don't rebound very well from drought. "

Some of the zooplankton have resting eggs that are deposited in mud. They rebound well when the ponds refill. Some frogs leave the pond when it dries up. Lots of different types of algae and one or two species of plant make it through, including one annual plant that makes lots of seeds, so when the pond refills again, it's ready to flourish.

Go elsewhere, or die

These tough species are incumbents, which gives them an advantage when the ponds refill. They can rebuff some of the new colonists. Niches get filled in the pond and colonists trying to join the club either go elsewhere or die.

"Drought homogenizes the variance among communities," Chase said. "It takes all these communities that used to be very different from each other and makes them very similar to each other. That's a very much underappreciated part of biodiversity."

Chase's findings are important to the study of biodiversity because he analyzed ponds both locally and regionally. A local analysis measures alpha diversity, which is the analysis of all the species in one pond. Chase, on the other hand, measured beta diversity, which measures the difference among ponds. If before the drought each pond had 10 species but only shared five in common, that difference is beta diversity.

"I found drought had less than a 10 percent reduction on local diversity, but a nearly 50 percent reduction on regional diversity. This is important because if you just count the number of species in any given pond you might say that drought had little effect on species diversity. But if you take exact data and you ask: Did drought affect regional diversity" I found it had a huge effect on regional diversity."

Most diversity studies only have looked at local communities, which in many cases rebound very quickly following disturbances. Thus, ecologists trying to restore wetlands, prairies, or forests, could get the impression that all is needed is to "build it and they will come." But Chase's findings show that community assembly can sometimes be much more random than that.

Chase's results have implications for wetland mitigation projects, which are often required by law. If a hundred acres of wetlands have been taken out by agriculture or a mall development, those one hundred wetland acres have to be created some place else. Ecologists are not sure exactly how to build functioning wetlands in the same way as the previous one, which had been assembled thousands of years ago. His findings give researchers better clues of how to go about restorations to restore biodiversity at both local and regional scales.

"I would argue that this has important implications for how to go about restoring and creating wetlands, and that in particular, we need to think about the role of stochasticity, leading to beta diversity among otherwise similar habitats, when we restore habitats."

 Chase's research was published in the Oct. 15 issue of Proceedings of the National Academy of Sciences. The National Science Foundation funds his work.


Story Source:

The above story is based on materials provided by Washington University in St. Louis. Note: Materials may be edited for content and length.


Cite This Page:

Washington University in St. Louis. "After Drought, Diversity Dries Up And Ponds All Look The Same." ScienceDaily. ScienceDaily, 17 October 2007. <www.sciencedaily.com/releases/2007/10/071015193426.htm>.
Washington University in St. Louis. (2007, October 17). After Drought, Diversity Dries Up And Ponds All Look The Same. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2007/10/071015193426.htm
Washington University in St. Louis. "After Drought, Diversity Dries Up And Ponds All Look The Same." ScienceDaily. www.sciencedaily.com/releases/2007/10/071015193426.htm (accessed August 20, 2014).

Share This




More Plants & Animals News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) — Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins